package com.rd.student.dashuju.sunwenzhuo.day0731;

import java.util.HashSet;

public class Test4 {
    public static void main(String[] args) {
        HashSet<Integer>set = new HashSet<>();
        while (set.size()<20){
            int num = (int)(Math.random()*50);
            set.add(num);
        }
        System.out.println(set);
    }
}
